Creating grass for large scenes

What is the best way to create realistic grass for a large scene, such as a distant hill? It needs to be realistic, but at the same time not too taxing on my computer’s resources.

Here is an example: (I want to create grass that looks like the top-right)

For distant shots, you only need a texture with some displacement, rather than real grass strands, which you could otherwise make very easily using particle physics.

Andrew Price has an example using his Grass Essentials, but it’s valid for any particle driven system. Basically, you use weight painting to control the distribution. As you won’t need as many particles in the distance to sell the effect, you have the higher density grass near the camera and tail off, with texture in the far distance as Anthony says after the particles fade off.